Vane cell pump

ABSTRACT

A vane cell pump which is used to pump fluids, comprises a rotor ( 2 ), a lift curve ring ( 3 ) and a plurality of wings( 4 ) which are pre-tensed by means of spring elements ( 5 ). The spring elements ( 5 ) are an integral part of the rotor.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation of copending InternationalApplication No. PCT/DE02/03154 filed Aug. 28, 2002 which designates theUnited States, and claims priority to German application no. 101 42712.3 filed Aug. 31, 2001.

TECHNICAL FIELD OF THE INVENTION

[0002] The invention relates to a vane cell pump for delivering fluidsand in particular a vane cell pump which is used as a pre-supply unitfor a common rail fuel injection system in motor vehicles.

DESCRIPTION OF THE RELATED ART

[0003] In reservoir-type fuel injection systems for motor vehicles, suchas common rail systems, a pre-supply pump is normally used in additionto a high-pressure pump. The pre-supply pumps employed for this purposeare generally vane cell pumps capable of providing the necessary flowdisplacement and a corresponding pressure increase, said vane cell pumpsin particular being capable of ensuring the necessary operating pointsrelatively well even at very low speeds (starter motor speed), the knownvane cell pumps being made from metal materials.

[0004] However, the disadvantage of the known vane cell pumps is that,at the relatively low speeds of approximately 75 RPM during starting ofa motor vehicle, the centrifugal force of the vanes alone isinsufficient to ensure that the vanes bear tightly against acorresponding cam contour of a ring of the pump. This produces a delayedpressure build-up or leaks resulting in efficiency losses duringstarting of the motor vehicle and therefore making the vehicle moredifficult or in some cases impossible to start. Moreover, it is possiblethat, at very high vane cell pump speeds, flow pulsations occur causingthe vanes to partly lift in partial angular regions of the cam contour.

SUMMARY OF THE INVENTION

[0005] The object of the present invention is therefore to provide avane cell pump that is of simple construction and easy and inexpensiveto manufacture, and which ensures that the vanes bear tightly against acam contour element.

[0006] According to the invention this object can be achieved by a vanecell pump for delivering fluids, comprising a rotor, a cam ring and aplurality of vanes which are pre-tensioned by means of spring elements,the spring elements being an integral part of the rotor, wherein therotor is made of plastic and the spring elements are captively moldedinto the rotor.

[0007] The object can also be achieved by a vane cell pump fordelivering fluids, comprising a plastic rotor having integrated springelements captively molded into the rotor, a cam ring, and a plurality ofvanes whereby the vanes are pre-tensioned by said spring elements.

[0008] The spring elements can be implemented as spring tongues or asspiral springs. The spring elements can be disposed on a ring. Thespring elements can be made of spring steel or plastic. The vanes and/orthe cam ring and/or a side plate and/or a pump casing can be made ofplastic. A duroplast can be used as the plastic material. The vane cellpump can be used as a pre-supply pump for a high-pressure pump of acommon rail injection system.

[0009] The vane cell pump according to the invention for deliveringfluids ensures that, irrespective of the speed, the vanes bearcontinuously against a ring providing the cam contour of the pump. Toachieve this, each vane is pre-tensioned outward by means of a springelement so that the vane bears continuously against the ring contour,the spring elements being implemented in such a way that they are anintegral part of the pump rotor. This means that the spring elements arecaptively connected to the rotor so that significant cost reductions canbe achieved particularly in terms of pump assembly. By means of thisone-piece implementation of rotor and spring elements, during theassembly process the rotor with incorporated spring elements can easilybe assembled as a sub-module, thereby obviating the need for laboriouslyplacing individual spring elements in the rotor.

[0010] It is particularly preferred that the rotor is made of plasticand the spring elements are captively molded into the rotor, therebyenabling the rotor in particular to be manufactured particularlyinexpensively. This combined with the assembly advantages provides acost reduction of over 40% compared to conventional vane cell pumps madeof metal. In particular, through the use of plastic, the machiningoperations necessary in the case of metal materials can also besignificantly reduced. Using plastic for the rotor in particular makesit possible to ensure that the spring elements are captively molded intothe rotor in such a way that no discontinuity is created in the rotorend faces. This ensures a homogeneous radial sealing length of the rotorto the adjacent parts of the pump.

[0011] Spring tongues or spiral springs are preferable used as springelements, said spring elements being disposed in such a way that theyare positioned in the bottom of slots in which the vanes move, so thatthe vanes are pre-tensioned outward by the spring elements.

[0012] According to a particularly preferred embodiment of the presentinvention, the spring elements are mounted on a ring, thereby enablingsaid spring elements likewise to be provided as a module. The springelements are disposed on the outer circumference of the ring and projectoutward. This considerably simplifies in particular the positioning ofthe spring elements, e.g. for molding of the rotor.

[0013] More advantageously still, the spring elements can be made fromspring steel or plastic. If the spring elements and the rotor are madeof plastic, the spring elements can be molded simultaneously with therotor (particularly preferred), thereby enabling further cost reductionsto be achieved.

[0014] In order also to achieve manufacturing cost reductions for othercomponents of the vane cell pump, the vanes and/or the cam ring and/or aside plate and/or a pump casing can be made from plastic, in particulara duroplast preferably being used as the plastic material.

[0015] The vane cell pump according to the invention is preferably usedin particular as a pre-supply pump for a reservoir-type fuel injectionsystem such as a common rail system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] A preferred embodiment of a vane cell pump according to thepresent invention will now be described with reference to theaccompanying drawings in which:

[0017]FIG. 1 shows a schematic cross-sectional view of a vane cell pumpaccording to an embodiment of the present invention;

[0018]FIG. 2 shows a schematic side view of the main components of thevane cell pump shown in FIG. 1;

[0019]FIG. 3 shows a cross-sectional view along the line B-B of FIG. 2;

[0020]FIG. 4 shows a cross-sectional view along the line A-A of FIG. 3;

[0021]FIG. 5 shows a partial cross-sectional view along the line C-C inFIG. 2;

[0022]FIG. 6 shows a perspective view of the spring element component;and

[0023]FIG. 7 shows a perspective exploded view of the main components ofthe vane cell pump.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] An embodiment of the present invention will now be described withreference to FIGS. 1 to 7.

[0025] As shown in FIG. 1, the vane cell pump comprises a rotor 2 whichis driven in the known manner via a drive shaft 9. As shown in FIGS. 4and 7, the rotor 2 contains a plurality of slots 10 in each of whichthere is disposed a vane 4, the vanes 4 moving in the radially formedslots 10.

[0026] As can be see from FIGS. 2 and 4, the rotor 2 is disposed in acam contour element implemented as a ring 3. As depicted in FIG. 1, thecam ring 3 is an integral part of a casing 8 of the vane cell pump.Note, however, that the cam ring 3 can also be implemented as a separatecomponent. The cam ring 3 is disposed eccentrically to the rotor 2 sothat the individual vanes form separate pump chambers in the knownmanner.

[0027] As can be seen particularly from FIGS. 2 and 3, a springcomponent comprising a spring ring 6 and spring elements 5 disposedthereon additionally forms an integral part of the rotor 2. FIG. 6 showsa perspective view of the spring component. The spring elements 5 aredisposed on the outer circumference of the ring 6 and provide a springforce in the radial direction of the ring 6. The spring component ismade from spring steel and can be easily manufactured by punching outand bending over the spring elements 5 by approximately 90° with respectto the ring surface.

[0028] The spring elements 5 are disposed in the slots 10 of the rotor 2in such a way that they pre-tension the vanes 4 radially outward,thereby ensuring that the vanes 4 bear against the contour of the ring 3in every position and at all speeds of the rotor 2 (cf. FIG. 2), therotor 2 being made of plastic and the spring component being completelymolded into the rotor as a pre-fabricated module. This implementation ofthe rotor additionally ensures that the two rotor end faces S, T (cf.FIG. 3) are homogeneously formed so as to ensure reliable sealing withrespect to adjacent components of the vane cell pump, e.g. to the casing8 and to a side plate 7 (cf FIG. 1).

[0029] The use of annular spring components with a plurality of springelements therefore ensures that the vanes 4 constantly bear against thecam contour and therefore no efficiency losses occur even during enginestarting at low RPM. This also minimizes any lifting of the vanes athigh engine speeds and the associated flow pulsations, the springelements 5 supporting the reverse hydraulic loading of the vanes 4.

[0030] In addition, as the spring elements 5 are an integral part of therotor 2, the assembly costs in particular can also be significantlyreduced, as no time-consuming positioning of the spring elements in theslots 10 of the rotor 2 is necessary. In particular a flow ratenecessary during starting for a high-pressure pump of a common-railinjection system for motor vehicles can therefore be provided accordingto the invention. Particularly by using plastic as the material forcomponents of the vane cell pump a surprisingly high manufacturing costsaving can be achieved compared to known vane cell pumps comprisingmetal components. The inventive combination of integral spring elementsin a rotor of the vane cell pump therefore provides major competitiveadvantages.

[0031] The present invention therefore relates to a vane cell pump fordelivering fluids, comprising a rotor 2, a cam ring 3 and a plurality ofvanes 4 which are pre-tensioned by means of spring elements 5, thespring elements 5 being an integral part of the rotor.

[0032] The present invention is not limited to the embodiment described.Various variations and changes can be made without departing from thescope of the invention.

I claim:
 1. A vane cell pump for delivering fluids, comprising a rotor,a cam ring and a plurality of vanes which are pre-tensioned by means ofspring elements, the spring elements being an integral part of therotor, wherein the rotor is made of plastic and the spring elements arecaptively molded into the rotor.
 2. The vane cell pump according toclaim 1, wherein the spring elements are implemented as spring tonguesor as spiral springs.
 3. The vane cell pump according to claim 1,wherein the spring elements are disposed on a ring.
 4. The vane cellpump according to claim 1, wherein the spring elements are made ofspring steel or plastic.
 5. The vane cell pump according to claim 1,wherein the vanes and/or the cam ring and/or a side plate and/or a pumpcasing are made of plastic.
 6. The vane cell pump according to claim 2,wherein a duroplast is used as the plastic material.
 7. The vane cellpump according to claim 1, wherein the vane cell pump is used as apre-supply pump for a high-pressure pump of a common rail injectionsystem.
 8. A vane cell pump for delivering fluids, comprising a plasticrotor having integrated spring elements captively molded into the rotor,a cam ring, and a plurality of vanes whereby the vanes are pre-tensionedby said spring elements.
 9. The vane cell pump according to claim 8,wherein the spring elements are implemented as spring tongues or asspiral springs.
 10. The vane cell pump according to claim 8, wherein thespring elements are disposed on a ring.
 11. The vane cell pump accordingto claim 8, wherein the spring elements are made of spring steel orplastic.
 12. The vane cell pump according to claim 8, wherein the vanesand/or the cam ring and/or a side plate and/or a pump casing are made ofplastic.
 13. The vane cell pump according to claim 9, wherein aduroplast is used as the plastic material.
 14. The vane cell pumpaccording to claim 8, wherein the vane cell pump is used as a pre-supplypump for a high-pressure pump of a common rail injection system.